Viscera:Uterus
The uterus is a hollow, thick-walled, muscular organ of the female reproductive tract that lies in the lesser pelvis. The uterus has an inverted pear shape, measuring 8x5x3cm. It weighs approximately 30-40g. The most common position of the uterus is anteverted (cervix angles forward) and anteflexed (body is flexed forward). It has a fundus, body and cervix. * Fundus: part of the uterus above the plane of the entrance of uterine tubes. It is convex and serous coat of pelvic peritoneum drapes over it. * Body: It is triangular in shaped and the cavity of the body is a mere slit. At the junction of fundus and body (cornu), the uterus receives the uterine tubes. Peritoneum that enclose the body, extend laterally as the broad ligament. * Cervix: the narrow canal that connects the vagina to the uterine cavity. ** The sulcus surrounding the protruding cervix is the fornix of the vagina. ** Posterior aspect of cervix is covered by peritoneum and related to Douglas pouch, whilst anterior is attached to the bladder above trigone by dense connective tissue. ** The internal os is the uterine opening, and external os is the vaginal opening of the cervix. Uterine suports and ligaments * anterior - pubocervical ligament * lateral - transverse cervical ligaments (Cardinal or Mackendrodt's) which are thickening of the base of the broad ligament extending from cervix to the side pelvic wall. Round ligament of uterus (pass through the deep inguinal ring and attached to the tissue of labium majoris) * posterior - uterosacral ligaments, attached to the Douglas pouch, rectum and front of sacrum * inferior - puborectalis and pubovaginalis parts of the levator ani muscle Relations * anteriorly - bladder; uterovesical pouch * posteriorly - rectum; pouch of Douglas * laterally - broad ligament; uterine vessels ** uterine tubes open into its upper part * inferiorly - uterine cavity communicates with that of the vagina Blood supply * arterial supply - dual supply from uterine arteries from the internal iliac and ovarian arteries from the aorta ** Uterine artery passes medially across the pelvic floor in the broad ligament to the cervix, supplies the vagina/cervix, then course upwards on sides of the uterus to the cornu, giving off branches. ** It anatomose with the tubal branch of the ovarian artery and join the contralateral uterine artery. ** Arcuate arteries run in the other myometrium from the uterine arteries and these give spiral arteries in endometrium. * venous drainage - uterine vein draining into internal iliac vein. It course below the artery and form a plexus across the pelvic floor. These communicate with vesical and rectal plexuses. eventually drain to either uterine or ovarian. * In pregnancy, arteries carry the blood to, and the veins convey it away from, the intervillous space of the placenta Nerve supply * Sympathetic from the branches of inferior hypogatric plexus, and ovarian plexus. * Pain fibres is carried by pelvic splanchnic and sympathetic nerves. Segment T10-L1. * Parasympathetic from the pelvic splanchnic nerves S2-S4 Lymphatic supply * upper body - internal external iliac nodes * lower body/cervix - superficial inguinal nodes (via round ligament) Variant anatomy * uterine agenesis: ~10% * arcuate uterus: often considered as part of normal anatomical variation, ~7% * unicornuate uterus: ~5-25% * uterine duplicational anomalies ** uterus didelphys: ~5-11% ** bicornuate uterus: ~10-39% ** septate uterus: ~34-55%